Modal Analysis on Baseball Bats: How Damping Rates Affect Overall "Feel"

Open Access
Suder, Robert John
Area of Honors:
Engineering Science
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Daniel Allen Russell, Thesis Supervisor
  • Lucas Jay Passmore, Honors Advisor
  • Baseball
  • Engineering
  • Sports
  • Acoustics
  • Vibrations
  • Modal Analysis
  • Damping
In the game of baseball, large amounts of energy are transferred during a collision between bat and ball. When a batter makes contact with a ball in the middle of the bat’s barrel, known as the "sweet spot," a maximum amount of energy is transferred to the ball. However, when contact is made outside of the sweet spot, energy is dissipated through vibrations in the bat, which causes an unpleasant stinging sensation in a player’s hands. For years, bat manufacturers have tried to find the balance of reducing vibration to eliminate this sting while still allowing enough vibration for a player to know when contact with the sweet spot is made. This balance is a large part of how a bat feels to a player. The research presented in this thesis investigates causes of sting from a bat and ball collision and examines ways sting can be measured. Damping rates of a selection of over 60 baseball and softball bats are tested experimentally to determine which materials and external methods used by manufacturers are most ecient in reducing vibrations. Ultimately, a group of players with an average 15 years experience will compare bats with dierent damping methods in practice and give feedback on what they "feel."